Sputtering is one of several well known techniques for applying or depositing a layer on a substrate. Generally, the substrate is placed in a deposition chamber which is evacuated or pressurized to a desired pressure. A particle flux of the coating material is generated within the chamber and the coating or deposition occurs by condensation of the particle flux onto the substrate surface.
In the ion beam bombardment sputtering technique, a high-energy source beam of ions is directed toward the target. The force of the bombarding ions imparts sufficient energy to the atoms of the target to cause the energized atoms to leave the target and form a particle flux. The resulting deposition upon a substrate forms a thin film.
Sputtering targets may be, for example, solid metallic blocks of a selected element or alloy. For sputtering of ceramic materials, targets may be dry powders made into a unitary porous structure. Other dry powder targets may be prepared by mixing the materials to be deposited into a binder-solvent slurry, casting the slurry into a mold, and applying heat to drive off the solvent and cure the binder. Such targets are prone to impurities (from the binder), frequent cracking from thermally-induced stresses, blistering (from embedded gasses), and difficulty in repairing targets damaged during the sputtering operation.